Flare with adhesive liner

ABSTRACT

An adhesive liner for bonding an illuminant candle of a flare to its case incorporates oxidizing materials and, optionally, material for coloring the light output thereof, whereby the formation of light-obscuring residue is not only prevented, but the brilliance and color of the flare may be enhanced.

United States Patent [1 1 Shaw et a1.

[ FLARE WITH ADHESIVE LINER [75] lnventors: Graham C. Shaw, Garland;Russell Reed, Jr., Brigham City, both of Utah [73] Assignee: ThiokolCorporation, Bristol, Pa.

[22] Filed: Aug. 14, 1973 [21] Appl. No.: 388,317

Related US. Application Data [63] Continuation of Ser. No. 138,780,April 29, 1971,

abandoned.

[52] U.S. Cl. 102/373; 102/103; 149/15 [51] Int. Cl. C06D 1/10 [58]Field of Search 149/15; 102/103, 37.8

[4 1 July 22,1975

[56] References Cited UNITED STATES PATENTS 3,749,023 7/1973 Kawaguchiet a1. 102/103 X Primary ExamirterStephen .l. Lechert, Jr. Attorney,Agent, or FirmEdward E. McCullough; Stanley A. Marcus 13 Claims, NoDrawings 1 FLARE WITH ADHESIVE LINER CROSS-REFERENCE TO RELATEDAPPLICATIONS This invention is related to that of a copendingapplication titled Castable Illuminant Flare Composition, Ser. No.144,679 filed Feb. 10, 1969 by V. T. Dinsdale et al. now US. Pat. No.3,723,206.

BACKGROUND OF THE INVENTION This invention relates to flares; and, morespecifically. to adhesive liners that bond the illuminant candles to theflare cases.

Although the present invention pertains to flares in general, it isparticularly concerned with colored signal flares, wherein thecombustible composition is diluted with coloring materials, and, hence,the combustion temperature is generally lower than that of illuminatingflares. The particular type of flare case with which the presentinvention is concerned comprises an aluminum tube lined with a kraftpaper tube in which the adhesive liner is applied. In colored signalflares, a persistent problem has been the formation of chimney-likeresidues around the burning illuminant candles, as a result of failureto burn the case and its adhesive liner completely. This residue tendsto obscure the light output of the flare, effectively limiting thepractical length thereof and, hence, the duration of its operationalusefulness.

The liner is customarily an elastomeric hydrocarbon bonding materialthat is primarily used to achieve a good bond between the illuminantcomposition and the case of the flare, so that combustion will beconfined to the exposed end of the flare candle and cannot progress downthe sides thereof, which occurs when the liner is absent or toothermally conductive. The conventional liner composition, beingprimarily an adhesive and a thermal insulation, is ordinarily deficientin oxidizers, so that its combustion uses oxidizer from the flarecandle, thereby further decreasing the light output of the flare.

SUMMARY OF THE INVENTION The present invention, which overcomes thesedisadvantages in prior art flares, is essentially an oxygenated adhesiveliner composition for flare cases. This improved liner not only containssufficient oxidizer to promote its own complete combustion and that ofthe case, so that light output of the flare is not obscured; but alsoenough to contribute to the brilliance of the flare.

The basic binder of the invention is an oxidizer-rich polymer, typicallyan elastomer similar to the binder of the illuminant composition. Theadded oxidizing coloring agent is chosen to be compatible with the colorof the flare. For example, sodium nitrate is used for yellow flares,strontium chloride for red, and barium nitrate or chloride for green.Appropriate curing agents are used for polymerizing the binder.Additional oxidizer, such as potassium perchlorate, may be included ifthe remainder of the liner composition is deficient in oxidizers.

Objects of the invention are to provide an adhesive liner for flaresthat provides a good bond between a flare candle and its case, that willburn completely at substantially the same rate as the illuminant candle,and that will avoid the problems of side burning and chimney formationby burning the case at the same rate as the illuminant candle. Animportant feature of the invention is that it may contribute both colorand light to the total output of the flare.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The typical flare constructionto which the present invention applies is described more thoroughly inthe application cited above, titled Castable Illuminant FlareComposition and Method for Making Flare Body Therewith, by V. T.Dinsdale et al. The flare case described therein comprises a kraft papertube inside an aluminum tube and coated on the inside with an adhesiveliner. The paper tube is filled with the illuminant and equipped with anigniter and deployment mechanisms.

An illuminant composition for red flares that is bonded to the flarecase by the adhesive liner of the present invention typically containsan elastomeric polymer for its binder, together with a suitable curingagent, ammonium perchlorate as an oxidizer, aluminum and/or magnesium ashigh-temperature fuels, and chromium octoate, strontium nitrate, andstrontium chloride as coloring and oxidizing agents. Such compositionsand their preparations are more thoroughly described in the cited,related application titled Illuminant Compositions for Colored Flares byG. C. Shaw et al.

A preferred formulation for an adhesive liner useful for bondingred-flare, illuminant candles to their cases is, in approximate parts byweight:

A preferred embodiment for an adhesive liner to be installed in yellowflares is, in approximate parts by weight:

WITCO Formrez F-17-8O (carboxylterminated polyester) 72.7 25.0 74.0ERLA-OS l0 (triglycidyl ether of paraamino phenol) 15.0 5.0 18.0chromium octoate 0.3 0.02 1.0 potassium perchlorate or sodium nitrate12.0 8.0 70.0

A preferred embodiment for an adhesive liner to be installed in greenflares is, in approximate parts by weight.

Carboxyl-terminated diethylene glycol succinate 34.9 Triglycidyl etherof trimethylol propane 13.0 Chromium octoate 0.4 Fused silicon dioxide1.7 Barium nitrate 35.0 Perchloropentacyclo (5.2.1.0 0. '.0"")

decane 15.0

In general, the binder of the present invention is a polymer that formsa good bond with both the illuminant candle and the flare case and has ahigh oxidizer content. Typical binders of this nature are carboxyl orhydroxyl terminated polyesters and polyethers. Added oxidizers may beany of those commonly used in pyrotechnic materials and solidpropellants, such as potassium pe chlorate, sodium nitrate. or ammoniumperchlorate.

The binder of the present invention is itself rich in oxidizer. This notonly promotes more efficient burning of the binder, but also it inhibitsthe formation of water in the combustion products, which tends to lowerthe flame temperature of the flare by dissociation. A preferred binder,sold under the trademark, WITCO Formrez F-17-80, is acarboxyl-terminated polyester derived from the esteriflcation ofsuccinic acid and triethylene glycol. It is cured with the trifunctionalepoxy sold under the trademark, ERLA-OS 10, (the triglycidyl ether oftrimethylolpropane) is also catalyzed with chromium octoate. Thetriglycidyl ether of trimethylolpropane is also catalyzed with chromiumoctoate. The triglycidyl ether of trimethylolpropane is also useful as acuring agent.

The liquid polymeric binder material used in practicing the inventionperferably is a mixture of liquid saturated polyester polymer and liquidepoxy resin. Preferably, the liquid saturated polyester polymer is acarboxyl-terminated polyester polymer such as a carboxylcontaining, lowmolecular weight, aliphatically saturated, substantially completelycondensed, polymeric polyester of a saturated aliphatic diol, adicarboxylic acid and a polyfunctional compound containing an averagefunctionality greater than two groups selected from the group consistingof polyols, polycarboxylic acids and polycarboxylic acid anahydrides,said polymeric polyester being liquid at a temperature between about 25and about 50C., having an acid content between about 0.1 and about 1.5milliequivalents per gram, an average of between about 2.5 and aboutcarboxylic groups per molecule, and average molecular weight betweenabout 700 to about 10,000 and free from hydroxyl groups. Such polymersare known and are taught, for example, in US. Pat. No. 3,182,041.Preferred liquid saturated polyester polymers are those having a highoxygen content combined with the carbon and hydrogen content of thepolymer. Especially preferred are liquid saturated polyester polymershaving a carbon to hydrogen to oxygen ratio of about 2 to 2.55 to 1 anda viscosity at 25C. of 480 to 520 poise. Polyesters prepared fromsaturated diacids, e.g. saturated fatty acids, such as succinic andglutaric acids and their anhydrides, are especially preferred.

Liquid epoxy resins and solutions thereof are also well known. The epoxyresins are formed by the reaction of a 1,2 epoxy compound and a dihydricphenol. The preferred 1,2-epoxy resins are prepared by the reaction ofepichlorhydrin with bis-phenol-A (2,2-bis-(4- hydroxyphenylypropane)generally in alkaline solution. A number of compounds may be used,including polyglycidyl ethers of ethylene glycol, propylene glycol,trimethylene glycol, diethylene glycol, triethylene glycol, glycerol,dipropylene glycol, etc. Similarly, other dihydric phenols may beemployed, including resorcinol, catechol, hydroquinone,4,4'-dihydroxybenzophenone, l-lbis-(4-hydroxyphenyl)-butane. 1,5dihydroxynaphthylene, para-aminophenal, trimethyol propane, etc. It isunderstood that the epoxy resins formed from the various reactantsmentioned above are not necessarily equivalent and, further, that theexact composition of the epoxy resins are dependent upon the molecularproportions of the epoxy compound and dihydric phenol employed in itspreparation. Preferred liquid epoxy resins are those having an epoxideequivalent (weight of resin in grams containing one gram of epoxy) ofabout to 210 and a viscosity of about 500 to 900 centipoises. When asolvent is used, organic solvents such as toluene, xylene and ketone,e.g., acetone, are preferably used. The liquid epoxy resin serves as acuring agent for the polyester polymer. Polyfunctional epoxy resin isespecially preferred, particularly, a trifunctional epoxy resin whereinthe functional group is hydroxyl or amino.

While the liquid epoxy resins are preferred as curing agents for thepolyester polymer, other polyfunctional curing agents may also be used,for example, polyfunctional aziridines, e.g., trifunctional derivativesof ethylenimine and other alkylenimine derivatives, and other curingagents such as those taught in US. Pat. No. 3,182,041.

The binder material is accelerated in its curing by the addition of asmall amount of catalyst for the curing agent. Preferably, the curingrate catalyst is a metal salt of a fatty acid, e.g., chromium octoate oriron linoleate. Such compounds are commonly referred to as metallicsoaps. They are insoluble soaps of such fatty acids as stearic,naphthenic, octoic, or Z-ethylhexoic, rosin (resinates) or tall oil(tallates) with the heavier metals such as aluminum, calcium, cadmium,copper, iron, lead, tin or zinc. Sufficient catalyst is used to obtain acuring rate which will give a pot life of about 8 to 24 hours. Theamount will usually be from about 0.5 to about 2.0 parts per 100 partsofliquid saturated polyester polymer, but may be more or less as founddesirable.

Generally, it is desirable that the amount of curing agent used bepresent in approximately stoichiometric mount relative to the polyesterpolymer, in order to provide complete cure of the polyester polymer. Theamount of catalyst used then controls the rate at which the cure occurs.

According to the present invention, the adhesive liner for yellow flarescontains potassium perchlorate or sodium nitrate, which oxidize thebinder and yield, in the case of sodium nitrate, sodium species whichemit light strongly in the yellow spectrum. The liner for red flarescontains strontium chloride, which yields efficient red coloringmaterial, and strontium nitrate, an oxidizing agent that yieldsstrontium species that also emit light in the red spectral ranges.Barium nitrate and/or chloride is used as the oxidizing agents in linersfor green flares.

EXAMPLE I A liner composition was prepared by mixing 72.7 parts byweight of carboxyl terminated diethylene glycol succinate prepolymerwith 15 parts of p-N, N- dipropylene oxide phenyl glycidyl ether and 0.3parts of chromium octoate. This mixture was stirred for about 15minutes, after which 12 parts of 6 to 20 micron potassium perchloratewas gradually added as stirring continued. After this composition wasthoroughly mixed, it was applied by brush to a kraft paper flare case toabout a 30-mil thickness. it was then placed in .an oven and cured at135F for about 3 days. The pyrotechnic composition for a red illuminantcandle was then cast in the tube and cured at elevated temperature foran appropriate length of time. When ignited, the liner and flare casewere observed to burn at approximately the same rate as the flarecandle, with no observable obscuration of the light output or colorthereof.

EXAMPLE 11 A mixture was made of 64 parts by weight ofcarboxyl-terminated diethylene glycol succinate prepolymer, 21 parts oftriglycidyl ether of trimethylopropane, one part of iron linoleate, andfour parts of fused silicon dioxide of submicron particle size. Whenthese ingredients were mixed thoroughly, 12 parts of 6 to 30 microndiameter potassium perchlorate was added gradually as stirringcontinued. The viscosity of the composition may be adjusted withinlimits by varying the quantity of silicon dioxide, to permit control ofthe tendency of the material to slump after it is applied to a surface.This composition was then diluted to a sprayable consistency by addingmethylene chloride. Any of several other volatile solvents may be usedfor this purpose. It was then applied to a flare case to an 0.60 inchthickness. The solvent evaporated rapidly and the remaining liner wascured at 135F for 4 days.

EXAMPLE III A premix was made of 40.4 parts by weight ofcarboxyl-terminated diethylene glycol succinate prepolymer, 15.1 partsof triglycidyl ether of trimethylopropane, 0.5 parts of chromiumoctoate, and two parts of submicron fused silicon dioxide. When theseingredients were thoroughly mixed, 28 parts of strontium nitrate having100 to 300 micron particle size and 14 parts of strontium chloridehaving to 100 particle size were added to the prepolymer composition asstirring continued. This material was then applied to a kraft paperflare case and was cured at 135F for 3 days. Pyrotechnic illuminantmaterial for a red flare was then cast into the case and cured in theusual manner. When the resulting flare was ignited, the intensity of thered color was not diluted or washed out as is usual with small-diameterflares having liner thicknesses greater than 15 mils.

EXAMPLE IV A liner for green flares was prepared by mixing 34.9 parts byweight of carboxyl terminated diethylene glycol succinate, 13 parts oftriglycidyl ether of trimethylol propane, 0.4 parts of chromium octoateand 1.7 parts of fused silicon dioxide. When these ingredients werethoroughly mixed, parts of barium nitrate and 15 parts ofperchloropentacyclo (521.0 5.0 .0 decane were added while mixingcontinued. The resulting composition was applied, as in the aboveexample, to a kraft paper flare case and was cured at 135F for 4 days.Green flare illuminant composition was then cast in the case and cured.Very satisfactory results were observed when the flare was burned.

We claim;

1. [n a flare having a tubular case and a colored illuminant compositionin the case, the improvement comprising an adhesive liner on the innersurface of the case to provide a bond and thermal insulation between thecase and the illuminant composition that will promote coextensive linearconsumption of case, liner, and

illuminant, comprising a cured mixture of:

a saturated, carboxyl-containing polyester, liquid polymeric binder; and

5 an oxidizer/coloring agent selected from the group consisting ofstrontium nitrate, potassium perchlorate, sodium nitrate, and bariumnitrate, the oxidizer being in stoichiometric deficiency and selectedfor color compatability with the illuminantthe color of theoxidizer/coloring agent being produced by the predominant flame spectrathereof.

2. The flare of claim 1 wherein the binder comprisescarboxyl-containing, low molecular weight, aliphatically saturated,substantially completely condensed, polymeric polyester of a saturatedaliphatic diol, a dicarboxylic acid, and a polyfunctional compoundcontaining an average of three functional groups selected from polyols,polycarboxylic acids and polycarboxylic acid anhydrides, the polymericpolyester being liquid at a temperature between about 25 C and 50 C,having an acid content between about 0.1 and 1.5 milliequivalents pergram, an average of between about 700 and 10,000 and free of hydroxylgroups. I

3. The flare of claim 1 in which the binder include a curing agentselected from the group consisting of triglycidyl derivative ofpara-amino phenol and triglydidyl ether of trimethylolpropane.

4. The flare of claim 1 wherein the coloring agent of the linercomprises strontium nitrate.

5. The flare of claim 1 wherein the coloring agent of the linercomprises barium nitrate.

6. The flare of claim 5 further including perchloropentacyclo (5.2.1.0,6.0 .0 decane, as a color enhancer in the liner.

7. The flare of claim 1 wherein the oxidizer of the liner comprisespotassium perchlorate.

8. The flare of claim 1 wherein the oxidizer of the liner comprisessodium nitrate.

40 9. The flare of claim 1 wherein the oxidizer of the liner comprises amixture of strontium nitrate and strontium chloride.

10. The flare of claim 1 wherein the liner composition comprises, inapproximate parts by weight:

LII

carboxyl-terminated diethylene 72.7 glycol succinate polymer p-N,N-dipropylene oxide phenyl glycidyl ether- 15.0 chronium octoate 0.3potassium perchlorate 12.0.

11. The flare of claim 1 wherein the liner composition comprises, inapproximate parts by weight:

carboxyl-terminated diethylene 64.0 glycol succinate polymer triglycidylether of trimethylolpropane 21.0 iron linoleate 1.0 fused silicondioxide (submicron particles) 4.0 potassium perchlorate 12.0.

12. The flare of claim 1 wherein the liner composition comprises, inapproximate parts by weight:

5 carboxyl-terminated diethylene 40.4

glycol succinate polymer triglycidyl ether of trimethylolpropane. 15.1chromium octoate 0.5 fused silicon dioxide (submicron particles) 2.0

-Continued strontium nitrate strontium chloride 13. The flare of claim 1wherein the liner composi- 5 tion comprises, in approximate parts byweight:

carboxyl-terminated diethylene

1. IN A FLARE HAVING A TUBULAR CASE AND A COLORED ILLUMINANT COMPOSITIONIN THE CASE, THE IMPROVEMENT COMPRISING AN ADHESIVE LINER ON THE INNERSURFACE OF THE CASE TO PROVIDE A BOND AND THERMAL INSULATOR BETWEEN THECASE AND THE ILLUMINANT COMPOSITION THAT WILL PROMOTE COEXTENSIVE LINEARCONSUMPTION OF CASE, LINER, AND ILLUMINANT, COMPRISING A CURED MIXTUREOF: A SATURATED, CARBOXYL-CONTAINING POLYESTER, LIQUID POLYMERIC BINDER,AND AN OXIDIZER/COLORING AGENT SELECTED FROM THE GROUP CONSISTING OFSTRONTIUM NITRATE, POTASSIUM PERCHLORATE, SODIUM NITRATE, AND BARIUMNITRATE, THE OXIDIZER BEING IN STOICHIOMETRIC DEFICIENCY AND SELECTEDFOR COLOR COMPATABILITY WITH THE ILLUMINANT- THE COLOR OF THEOXIDIZER/COLORING AGENT BEING PRODUCED BY THE PREDOMINANT FLAME SPECTRATHEREOF.
 2. The flare of claim 1 wherein the binder comprisescarboxyl-containing, low molecular weight, aliphatically saturated,substantially completely condensed, polymeric polyester of a saturatedaliphatic diol, a dicarboxylic acid, and a polyfunctional compoundcontaining an average of three functional groups selected from polyols,polycarboxylic acids and polycarboxylic acid anhydrides, the polymericpolyester being liquid at a temperature between about 25* C and 50* C,having an acid content between about 0.1 and 1.5 milliequivalents pergram, an average of between about 700 and 10,000 and free of hydroxylgroups.
 3. The flare of claim 1 in which the binder includes a curingagent selected from the group consisting of triglycidyl derivative ofpara-amino phenol and triglydidyl ether of trimethylolpropane.
 4. Theflare of claim 1 wherein the coloring agent of the liner comprisesstrontium nitrate.
 5. The flare of claim 1 wherein the coloring agent ofthe liner comprises barium nitrate.
 6. The flare of claim 5 furtherincluding perchloropentacyclo (5.2.1.02,6.03,9.05,8) decane, as a colorenhancer in the liner.
 7. The flare of claim 1 wherein the oxidizer ofthe liner comprises potassium perchlorate.
 8. The flare of claim 1wherein the oxidizer of the liner comprises sodium nitrate.
 9. The flareof claim 1 wherein the oxidizer of the liner comprises a mixture ofstrontium nitrate and strontium chloride.
 10. The flare of claim 1wherein the liner composition comprises, in approximate parts by weight:11. The flare of claim 1 wherein the liner composition comprises, inapproximate parts by weight:
 12. The flare of claim 1 wherein the linercomposition comprises, in approximate parts by weight:
 13. The flare ofclaim 1 wherein the liner composition comprises, in approximate parts byweight: